1. Field of the Invention
The present invention relates to a method for manufacturing a silicon on insulator (SOI) substrate and a method for manufacturing a semiconductor device.
2. Description of the Related Art
In recent years, LSI technology has been dramatically progressed, and an SOI structure which is capable of realizing speeding up and low power consumption has been attracted attention. This technology allows an active region (channel formation region) of a field effect transistor (FET), which has been conventionally formed using bulk single crystal silicon, to be formed using a single crystal silicon thin film. It is known that a MOS field effect transistor manufactured using an SOI structure has lower parasitic capacitance than a conventional field effect transistor manufactured using a bulk single crystal silicon substrate, which is an advantage in increasing speed.
As examples of a substrate having an SOI structure (also referred to as an SOI substrate), a SIMOX substrate, a bonded substrate, and the like are given. For example, a SIMOX substrate obtains an SOI structure through the following manner: oxygen ions are implanted into a single crystal silicon substrate and heat treatment is performed at 1300° C. or higher in order to form a buried oxide (BOX) film, whereby a single crystal silicon thin film is formed on the surface of the buried oxide film. In the SIMOX substrate, oxygen ion implantation can be controlled precisely, and thus a single crystal silicon thin film having a uniform thickness can be formed with high control; however, there is a problem in time and costs because it is necessary to take a long time for oxygen ion implantation. In addition, there is another problem in that a single crystal silicon thin film is easily damaged in oxygen ion implantation.
A bonded substrate obtains an SOI structure through the following manner: two single crystal silicon substrates (a base substrate and a bond substrate) are bonded to each other with an oxide film interposed therebetween, and one of the single crystal silicon substrates (the bond substrate) is thinned by grinding and polishing on its rear side (a plane which is not a surface to be bonded), whereby a single crystal silicon thin film is formed. Since it is difficult to form a uniform thin single crystal silicon thin film by grinding and polishing, a technique called a Smart Cut (registered trademark) method for thinning a film, which employs hydrogen ion implantation (e.g., see Reference 1: Japanese Published Patent Application No. H5-211128) is proposed.
Further, a method for forming a single crystal silicon layer over a supporting substrate made of glass by using such a Smart Cut method has been proposed (e.g., see Reference 2: Japanese Published Patent Application No. H11-163363).
Furthermore, in order to increase productivity of semiconductor devices using SOI substrates and to provide large-sized semiconductor devices, an SOI substrate having a larger size has been desired. For example, Reference 3 (Japanese Published Patent Application No. 2003-257804) proposes a method for manufacturing a large-sized SOI substrate in which a plurality of silicon wafers is arranged over a large-sized supporting substrate and is bonded to each other and an epitaxially grown film is formed over the plurality of silicon wafers, whereby a large-sized SOI substrate is manufactured.